This pilot episode was based on the Ellery Queen novel The Fourth Side of the Triangle.

This pilot introduces the audience to the character of Simon Brimmer who would appear on a recurring basis. Brimmer was a radio actor who starred in a mystery show and always tried to beat Ellery Queen to the solution of the case.

Simon Brimmer's first radio play features Dr. Flemming. Dr. Flemming is the killer in the stage play Prescription: Murder by Ellery Queen series creators Richard Levinson and William Link, featuring Lieutenant Columbo, and was the basis for the pilot for that series.

Ellery: Unfortunately, Mr. Brimmer, you're asking me to be a ghost writer.
Simon Brimmer: A technicality.
Ellery: Not to me.
Simon Brimmer: Well, all right then, let's say a very rich ghost. With silk sheets.

Simon Brimmer: Something important?
Ellery: I don't know. Anyway, Mr. Brimmer, thanks for your offer. I'm sorry it didn't work out.
Simon Brimmer: I hope you know you're making a mistake.
Ellery: Oh, probably. I make a lot of them.

(to Ellery)
Inspector Queen: Almost as far-fetched as one of your books. A dying clue, which makes absolutely no sense. Which means of course it's right up your alley.

Ellery: Tell me about her.
Inspector Queen: Name's, uh, Monica Gray. One of the top fashion designers since the war. Your wife would probably be wearing her fall line. If you were married.

(as Ellery examines a television)
Inspector Queen: You ever see one of those things before?
Ellery: Eh? A few.
Inspector Queen: Damn nuisance. Friend of mine has one. People keep dropping in.
Ellery: Oh, I wouldn't worry about it. It's just a passing fad.

Ellery: Wait a minute.
Inspector Queen: You got something.
Ellery: Very clever, Dad, very shrewd.
Inspector Queen: Who, who?
Ellery: You. You know I'm supposed to be home, finishing a book, you know I got a deadline to meet, but you drag me up here and you dangle all this catnip in front of me.
Inspector Queen: Now, Ellery, I'm not trying...
Ellery: That's it, I'm going home. You're not gonna suck me in this time.
Inspector Queen: Son, you're doing me an injustice. Besides, I know you. Let's face it, you're hooked! You can't walk out of here!
Ellery: Goodnight, Dad. (leaves)
Velie: Ah, gee, that's too bad, Inspector. I thought you had him out of the water and into the boat! (Inspector Queen gestures him to wait, Ellery walks back in)
Ellery: I was just thinking....

Inspector Queen: I guess I got my money's worth.
Ellery: It's really very simple. I, I make it a point to be observant, and to pay attention to details. Goodnight, Dad.
Inspector Queen: Son? You forgot your glasses.

Ellery: You shouldn't be seen in public with me.
Gail Stevens: Why not?
Ellery: Because I'm incredibly stupid.

Inspector Queen: I'm doing my job! Now, if you don't have some hard facts, and I mean something better than the last chapter in a mystery book, you'd better go home and burn yourself some lunch.
Ellery: That's what I like about you, Dad! You've got such a nice, open mind!

Ellery: Velie? I've got a personal problem and so has this department.
Velie: What's that, Maestro?
Ellery: My father is dangerously close to becoming senile!
Inspector Queen: I heard that, and I want you to know I'm changing my will!

District Attorney: Except now we have no suspects and no leads. Satisfied, Ellery?
Ellery: Nah, not really. this is the only case where I spend all my time proving who didn't commit a murder.

Inspector Queen: Maybe I ought to take the gold watch and retire.
Ellery: Maybe you should get a good night's sleep. Come on, Dad. I'll drive you home.
Inspector Queen: Son. You're my only child, and a comfort in my old age...
Police Officer: Inspector!
Inspector Queen: Yeah? But you are the worst driver in the world. If anybody gets behind that wheel, it'll be me.

Ellery: Thank you, everybody, come on, Dad, let's go home.
Inspector Queen: Well, I can't. I've gotta go down to Gramercy Park. Somebody just murdered a millionaire art collector. Just your kind of case, Ellery.
Ellery: Good night, Dad.
Inspector Queen: Really, very strange. Thirty paintings in the house, all of them turned to the wall.
Ellery: Oh, no, no, no. See you at breakfast!
Inspector Queen: What harm would it do to take a look?
Ellery: Did you say thirty paintings turned to the wall?
Inspector Queen: Yeah.

In the opening scene, when Monica pulls out the plugs, the wall socket is fitted for 3-prong grounded plugs. The socket and plug didn't become part of standard construction code until 1962.

When Ellery picks up the framed photo of Monica in her apartment, the closeup reveals a woman wearing a black blouse. However, when he sets it done, it instantly becomes a photo of a woman wearing a white blouse, sitting on a visible chair.

When Carson first tells Ellery about the disguise he wore to visit Monica, he says he wore, "a false mustache, glasses, and a funny hat." But later when Ellery reminds him that he wore a disguise and they need to alter the identification photo, Carson says that he wore makeup.